The Skeptic's Toolbox

Always ask whether the hypothesis can be, at least in principle, falsified. Propositions that are untestable, unfalsifiable are not worth much. Consider the grand idea that our Universe and everything in it is just an elementary particle--an electron, say--in a much larger Cosmos. But if we can never acquire information for outside our Universe, is not the idea incapable of disproof? You must be able to check assertions out. Inveterate skeptics must be given the chance to follow your reasoning,

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Occam's Razor. This convenient rule-of-thumb urges us when faced with two hypotheses that explain the data equally well to choose the simpler.

~Carl Sagan, The Demon-Haunted World

It's worth adding that it's very rare to find two hypotheses that explain the data equally well .

If there's a chain of argument, every link in the chain must work, including the premise.

~Carl Sagan, The Demon-Haunted World

This is pretty basic logic, but there are plenty of folks who try to get around this and insert a whole slew of logical fallacies in their argument to try and save one link. An argument is as strong as its weakest link.

Quantify. If whatever you're explaining has some measure, some numerical quantity attached to it, you'll be much better to discriminate among competing hypotheses. What is vague and qualitative is open to many explanations. Of course there are truths to be sought in the many qualitative issues with are obliged to confront, but finding them is more challenging.

~Carl Sagan, The Demon-Haunted World

This is the basis for many sciences, including the one I am involved ...

Try not to get overly attached to a hypothesis just because it's yours. It's only a way station in the pursuit of knowledge. Ask yourself why you like the idea. Compare it fairly with the alternatives. See if you can find reasons for rejecting it. If you don't, others will.

~Carl Sagan, The Demon-Haunted World

I once believed in the existence of the Christian God. It was a great idea, a loving caring parental figure, everlasting life in a great place if I was ...